一些重要struct

//+++++++++++struct列表+++++++++++++++++++++++++++++++++++++++++++

struct mm_struct ;
struct vm_area_struct


 /*這個參考《深入理解LINUX內存管理》學習筆記 */

typedef struct pglist_data;

struct zone;

struct page;


//++++++++++++以下是個struct的詳細解析++++++++++++++++++++++++++++++++++

//struct mm_struct 可以由

current->mm

或者

task = get_proc_task(file->f_path.dentry->d_inode); //get_pid_task(proc_pid(inode), PIDTYPE_PID);

mm = get_task_mm(task);

得到。

struct mm_struct{
	struct vm_area_struct * mmap;	/* 這個鏈表鏈接了屬於這個內存描述符的所有 vm_area_struct 結構體。*/
	struct rb_root mm_rb;                      /* 由於屬於一個內存描述符的內存區域可能非常多,爲了加快內存區域的查找以及添加刪除等操作的速度,內核用 mm_rb 表示一棵鏈接了所有內存區域的紅黑樹。*/
       /*mmap 和 mm_rb 是用兩種不同的數據結構表示同一批數據。*/

 struct vm_area_struct * mmap_cache;	;/* 指向最後一個引用的線性區對象*/
#ifdef CONFIG_MMU
  /* 在進程地址空間中搜索有效線性地址區間的方法   */
	unsigned long (*get_unmapped_area) (struct file *filp,
				unsigned long addr, unsigned long len,
				unsigned long pgoff, unsigned long flags);
#endif
	unsigned long mmap_base;		/* base of mmap area */
	unsigned long mmap_legacy_base;         /* base of mmap area in bottom-up allocations */
	unsigned long task_size;		/* size of task vm space */
	unsigned long highest_vm_end;		/* highest vma end address */
	pgd_t * pgd;  /*    指向頁全局目錄   */

        atomic_t mm_users;			
        atomic_t mm_count;			
/*每一個進程如果擁有一個內存描述符,則會增
加 mm_users 的計數,所有 mm_users 的計數只相當於 mm_count 的一個計數。比如
n 個 Linux 線程共享同一個內存描述符,那麼對應的內存描述符的 mm_users 計數則爲
n,而 mm_count 則可能只是 1。如果有內核執行序列想要訪問一個內存描述符,則該
執行序列先增加 mm_count 的計數,使用結束後減少 mm_count 的計數。一但
mm_count 減爲 0,表示該內存描述符沒有任何引用,則它會被內核銷燬。*/


 int map_count;				/* number of VMAs */    /*  線性區的個數   */

	spinlock_t page_table_lock;		/* Protects page tables and some counters */

        struct rw_semaphore mmap_sem;
/*mmap_sem 是一個讀寫鎖,凡是需要操作內存描述符中的內存區域時,則需要先得到
相應的讀鎖或者寫鎖,使用結束後釋放該鎖*/

	struct list_head mmlist;		/* List of maybe swapped mm's.	These are globally strung
						 * together off init_mm.mmlist, and are protected
						 * by mmlist_lock
						 */
/*mm_list 字段是一個循環雙鏈表。它鏈接
了系統中所有的內存描述符。*/


	unsigned long hiwater_rss;	/* High-watermark of RSS usage */   /*  進程所擁有的最大頁框數   */
	unsigned long hiwater_vm;	 /*   進程線性區中的最大頁數    */

	unsigned long total_vm;		/* Total pages mapped */
	unsigned long locked_vm;	/* Pages that have PG_mlocked set */  /*"鎖住"而不能換出的頁的個數*/
	unsigned long pinned_vm;	/* Refcount permanently increased */
	unsigned long shared_vm;	/* Shared pages (files) */  /*共享文件內存映射中的頁數*/
	unsigned long exec_vm;		/* VM_EXEC & ~VM_WRITE */ /*可執行內存映射中的頁數*/
	unsigned long stack_vm;		/* VM_GROWSUP/DOWN */  /*用戶態堆棧中的頁數*/
	unsigned long def_flags;
	unsigned long nr_ptes;		/* Page table pages */
	unsigned long start_code, end_code, start_data, end_data; /*代碼段的起始地址,代碼段的最後地址,數據段的起始地址和數據段的最後的地址*/
	unsigned long start_brk, brk, start_stack;/*堆的起始地址,堆的當前最後地址,用戶態堆棧的起始地址*/ 
	unsigned long arg_start, arg_end, env_start, env_end;/*命令行參數的起始地址,命令行參數的最後地址,環境變量的起始地址,環境變量的最後地址*/

	unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */     /*    開始執行ELF程序時會使用到saved_auxv參數   */

	/*
	 * Special counters, in some configurations protected by the
	 * page_table_lock, in other configurations by being atomic.
	 */
	struct mm_rss_stat rss_stat;	

	struct linux_binfmt *binfmt;

	cpumask_var_t cpu_vm_mask_var;

	/* Architecture-specific MM context */
	mm_context_t context;

	unsigned long flags; /* Must use atomic bitops to access the bits */

	struct core_state *core_state; /* coredumping support */
#ifdef CONFIG_AIO
	spinlock_t		ioctx_lock;
	struct hlist_head	ioctx_list;
#endif
#ifdef CONFIG_MM_OWNER
	/*
	 * "owner" points to a task that is regarded as the canonical
	 * user/owner of this mm. All of the following must be true in
	 * order for it to be changed:
	 *
	 * current == mm->owner
	 * current->mm != mm
	 * new_owner->mm == mm
	 * new_owner->alloc_lock is held
	 */
	struct task_struct __rcu *owner;
#endif

	/* store ref to file /proc/<pid>/exe symlink points to */
	struct file *exe_file;
#ifdef CONFIG_MMU_NOTIFIER
	struct mmu_notifier_mm *mmu_notifier_mm;
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
	pgtable_t pmd_huge_pte; /* protected by page_table_lock */
#endif
#ifdef CONFIG_CPUMASK_OFFSTACK
	struct cpumask cpumask_allocation;
#endif
#ifdef CONFIG_NUMA_BALANCING
	/*
	 * numa_next_scan is the next time that the PTEs will be marked
	 * pte_numa. NUMA hinting faults will gather statistics and migrate
	 * pages to new nodes if necessary.
	 */
	unsigned long numa_next_scan;

	/* numa_next_reset is when the PTE scanner period will be reset */
	unsigned long numa_next_reset;

	/* Restart point for scanning and setting pte_numa */
	unsigned long numa_scan_offset;

	/* numa_scan_seq prevents two threads setting pte_numa */
	int numa_scan_seq;

	/*
	 * The first node a task was scheduled on. If a task runs on
	 * a different node than Make PTE Scan Go Now.
	 */
	int first_nid;
#endif
#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
	/*
	 * An operation with batched TLB flushing is going on. Anything that
	 * can move process memory needs to flush the TLB when moving a
	 * PROT_NONE or PROT_NUMA mapped page.
	 */
	bool tlb_flush_pending;
#endif
	struct uprobes_state uprobes_state;
};


//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


struct vm_area_struct  
{  
struct mm_struct * vm_mm; /*指向該 VMA 屬於的內存描述符。*/  
unsigned long vm_start; /*虛擬區開始的地址*/  
unsigned long vm_end; /*虛擬區結束的地址,但不包括 vm_end 指向的地址,即vm_end 是虛擬內存區域的最後一個有效字節的後一個字節。*/  
struct vm_area_struct *vm_next;/*鏈接虛存區*/  
pgprot_t vm_page_prot; /*虛存區的保護權限*/  
unsigned long vm_flags; /*虛存區的標誌*/  
short vm_avl_height;/*AVL的高度*/  
struct vm_area_struct * vm_avl_left; /*左虛存區節點*/  
struct vm_area_struct * vm_avl_right;/*右虛存區節點*/  
struct vm_area_struct *vm_next_share;  
struct vm_area_struct **vm_pprev_share;  
struct vm_operations_struct * vm_ops;/*對虛存區操作的函數*/  
unsigned long vm_pgoff; /* 映射文件中的偏移量*/  
struct file * vm_file;/*vm_file 是該內存區域對應的文件,如果內存區域是匿名的,則該字段被置爲 NULL。*/  
unsigned long vm_raend;/  
voidvoid * vm_private_data; /*指向內存區的私有數據*/  
}; 

//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

http://blog.chinaunix.net/attachment/201205/23/26874138_13377627933ECr.png



//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


typedef struct pglist_data {
	struct zone node_zones[MAX_NR_ZONES];          /*節點中的管理區 分別爲ZONE_DMA,ZONE_NORMAL,ZONE_HIGHMEM*/

/*list中zone的順序代表了分配內存的順序,前者分配內存失敗將會到後者的區域中分配內存;
當調用free_area_init_core()時,由mm/page_alloc.c文件中的build_zonelists()函數設置*/
	struct zonelist node_zonelists[MAX_ZONELISTS]; 

	int nr_zones;    				 /*節點中管理區的數目,不一定爲3個,有的節點中可能不存在ZONE_DMA*/
#ifdef CONFIG_FLAT_NODE_MEM_MAP			 /* means !SPARSEMEM */
	struct page *node_mem_map;  /*node中的第一個page,它可以指向mem_map中的任何一個page*/
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
	struct page_cgroup *node_page_cgroup;
#endif
#endif
	struct bootmem_data *bdata;/*這個僅用於boot 的內存分配*/
#ifdef CONFIG_MEMORY_HOTPLUG
	/*
	 * Must be held any time you expect node_start_pfn, node_present_pages
	 * or node_spanned_pages stay constant.  Holding this will also
	 * guarantee that any pfn_valid() stays that way.
	 *
	 * Nests above zone->lock and zone->size_seqlock.
	 */
	spinlock_t node_size_lock;
#endif
	unsigned long node_start_pfn;     /*pfn是page frame number的縮寫。這個成員是用於表示node中的開始那個page在物理內存中的位置的;  該節點的起始頁框編號*/
	unsigned long node_present_pages; /* total number of physical pages ;node中的真正可以使用的page數量*/
	unsigned long node_spanned_pages; /* total size of physical page  range, including holes ;   */
	int node_id;                      /*節點標識符,代表當前節點是系統中的第幾個節點*/
	wait_queue_head_t kswapd_wait;    /*頁換出進程使用的等待隊列*/
	struct task_struct *kswapd;       /*指向頁換出進程的進程描述符*/
	int kswapd_max_order;             /*kswapd將要創建的空閒塊的大小取對數的值*/
}


//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


struct zone {
	/* Fields commonly accessed by the page allocator */

	/* zone watermarks, access with *_wmark_pages(zone) macros */
	unsigned long watermark[NR_WMARK];/*該管理區的三個水平線值,min,low,high*/

	/*
	 * When free pages are below this point, additional steps are taken
	 * when reading the number of free pages to avoid per-cpu counter
	 * drift allowing watermarks to be breached
	 */
	unsigned long percpu_drift_mark;

	/*
	 * We don't know if the memory that we're going to allocate will be freeable
	 * or/and it will be released eventually, so to avoid totally wasting several
	 * GB of ram we must reserve some of the lower zone memory (otherwise we risk
	 * to run OOM on the lower zones despite there's tons of freeable ram
	 * on the higher zones). This array is recalculated at runtime if the
	 * sysctl_lowmem_reserve_ratio sysctl changes.
	 */
	 /*每個管理區必須保留的頁框數*/ /*爲了防止一些代碼必須運行在低地址區域,所以事先保留一些低地址區域的內存*/
	unsigned long		lowmem_reserve[MAX_NR_ZONES]; 

#ifdef CONFIG_NUMA           /*如果定義了NUMA*/
	int node;           /*該管理區所屬節點的節點號*/
	/*
	 * zone reclaim becomes active if more unmapped pages exist.
	 */
	unsigned long		min_unmapped_pages;  /*當可回收的頁面數大於該變量時,管理區將回收頁面*/
	unsigned long		min_slab_pages;      /*同上,只不過該標準用於slab回收頁面中*/
	struct per_cpu_pageset	*pageset[NR_CPUS];   /*每個CPU使用的頁面緩存*/
#else
	struct per_cpu_pageset	pageset[NR_CPUS];
#endif
	/*
	 * free areas of different sizes
	 */
	spinlock_t		lock;       /*保護該管理區的自旋鎖*/
#ifdef CONFIG_MEMORY_HOTPLUG
	/* see spanned/present_pages for more description */
	seqlock_t		span_seqlock;
#endif
	struct free_area	free_area[MAX_ORDER];/*標識出管理區中的空閒頁框塊;    頁面使用狀態的信息,以每個bit標識對應的page是否可以分配*/

#ifndef CONFIG_SPARSEMEM
	/*
	 * Flags for a pageblock_nr_pages block. See pageblock-flags.h.
	 * In SPARSEMEM, this map is stored in struct mem_section
	 */
	unsigned long		*pageblock_flags;
#endif /* CONFIG_SPARSEMEM */


	ZONE_PADDING(_pad1_)

	/* Fields commonly accessed by the page reclaim scanner */
	spinlock_t		lru_lock;	/*(最近最少使用算法)的自旋鎖*/
	struct zone_lru {
		struct list_head list;
	} lru[NR_LRU_LISTS];
    
	struct zone_reclaim_stat reclaim_stat; /*頁面回收的狀態*/

	/*管理區回收頁框時使用的計數器,記錄到上一次回收,一共掃過的頁框數*/
	unsigned long		pages_scanned;	   /* since last reclaim */
	unsigned long		flags;		   /* zone flags, see below */

	/* Zone statistics */
	atomic_long_t		vm_stat[NR_VM_ZONE_STAT_ITEMS];

	/*
	 * prev_priority holds the scanning priority for this zone.  It is
	 * defined as the scanning priority at which we achieved our reclaim
	 * target at the previous try_to_free_pages() or balance_pgdat()
	 * invokation.
	 *
	 * We use prev_priority as a measure of how much stress page reclaim is
	 * under - it drives the swappiness decision: whether to unmap mapped
	 * pages.
	 *
	 * Access to both this field is quite racy even on uniprocessor.  But
	 * it is expected to average out OK.
	 */
	int prev_priority;

	/*
	 * The target ratio of ACTIVE_ANON to INACTIVE_ANON pages on
	 * this zone's LRU.  Maintained by the pageout code.
	 */
	unsigned int inactive_ratio;


	ZONE_PADDING(_pad2_)
	/* Rarely used or read-mostly fields */

	/*
	 * wait_table		-- the array holding the hash table
	 * wait_table_hash_nr_entries	-- the size of the hash table array
	 * wait_table_bits	-- wait_table_size == (1 << wait_table_bits)
	 *
	 * The purpose of all these is to keep track of the people
	 * waiting for a page to become available and make them
	 * runnable again when possible. The trouble is that this
	 * consumes a lot of space, especially when so few things
	 * wait on pages at a given time. So instead of using
	 * per-page waitqueues, we use a waitqueue hash table.
	 *
	 * The bucket discipline is to sleep on the same queue when
	 * colliding and wake all in that wait queue when removing.
	 * When something wakes, it must check to be sure its page is
	 * truly available, a la thundering herd. The cost of a
	 * collision is great, but given the expected load of the
	 * table, they should be so rare as to be outweighed by the
	 * benefits from the saved space.
	 *
	 * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
	 * primary users of these fields, and in mm/page_alloc.c
	 * free_area_init_core() performs the initialization of them.
	 */
	wait_queue_head_t	* wait_table;   /*等待一個page釋放的等待隊列哈希表。它會被wait_on_page(),unlock_page()函數使用. 用哈希表,而不用一個等待隊列的原因,防止進程長期等待資源。*/
	unsigned long		wait_table_hash_nr_entries;   /*散列表數組的大小*/
	unsigned long		wait_table_bits;              /*散列表數組的大小對2取log的結果*/

	/*
	 * Discontig memory support fields.
	 */
	struct pglist_data	*zone_pgdat;              /*管理區所屬節點 ;指向這個zone所在的pglist_data對象*/

	unsigned long		zone_start_pfn; /*管理區的起始頁框號  zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */

    /*
     * spanned_pages is the total pages spanned by the zone, including
     * holes, which is calculated as:
     *  spanned_pages = zone_end_pfn - zone_start_pfn;
     *
     * present_pages is physical pages existing within the zone, which
     * is calculated as:
     *  present_pages = spanned_pages - absent_pages(pages in holes);
     *
     * managed_pages is present pages managed by the buddy system, which
     * is calculated as (reserved_pages includes pages allocated by the
     * bootmem allocator):
     *  managed_pages = present_pages - reserved_pages;
     *
     * So present_pages may be used by memory hotplug or memory power
     * management logic to figure out unmanaged pages by checking
     * (present_pages - managed_pages). And managed_pages should be used
     * by page allocator and vm scanner to calculate all kinds of watermarks
     * and thresholds.
     *
     * Locking rules:
     *
     * zone_start_pfn and spanned_pages are protected by span_seqlock.
     * It is a seqlock because it has to be read outside of zone->lock,
     * and it is done in the main allocator path.  But, it is written
     * quite infrequently.
     *
     * The span_seq lock is declared along with zone->lock because it is
     * frequently read in proximity to zone->lock.  It's good to
     * give them a chance of being in the same cacheline.
     *
     * Write access to present_pages at runtime should be protected by
     * lock_memory_hotplug()/unlock_memory_hotplug().  Any reader who can't
     * tolerant drift of present_pages should hold memory hotplug lock to
     * get a stable value.
     *
     * Read access to managed_pages should be safe because it's unsigned
     * long. Write access to zone->managed_pages and totalram_pages are
     * protected by managed_page_count_lock at runtime. Idealy only
     * adjust_managed_page_count() should be used instead of directly
     * touching zone->managed_pages and totalram_pages.
     */


	/*這個地方參考free_area_init_core()*/
	unsigned long		spanned_pages;	/*管理區的大小,包括洞*/
	unsigned long		present_pages;	/*管理區的大小,不包括洞,  可能包含dma_reserve,以及mem_map結構提所佔用的;*/
	unsigned long              managed_pages;   

	/*
	 * rarely used fields:
	 */
	const char		*name; /*指向管理區的名稱,爲"DMA","NORMAL"或"HighMem"*/
}


//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


struct page {
    /* First double word block */
    unsigned long flags;        /*flags 字段存儲了頁面的狀態信息,例如:表示頁面剛被寫了數據的髒位;
該頁面是否被鎖定在內存中不充許置換到交換分區的標誌。*/

/*
爲空表示該頁屬於交換高速緩存;
mapping字段非空,且最低位是1,mapping字段中存放的是指向anon_vma描述符的指針,表示該頁爲匿名頁;
mapping字段非空,且最低位是0,mapping字段指向對應文件的address_space對象,表示該頁爲映射頁;
*/
    struct address_space *mapping;  /* If low bit clear, points to
                     * inode address_space, or NULL.
                     * If page mapped as anonymous
                     * memory, low bit is set, and
                     * it points to anon_vma object:
                     * see PAGE_MAPPING_ANON below.
                     */


    /* Second double word */
    struct {
        union {
/*這個成員根據page的使用的目的有2種可能的含義。
第一種情況:如果page是file mapping的一部分,它指明在文件中的偏移。如果page是交換緩存,則它指明在address_space所聲明的對象:swapper_space(交換地址空間)中的偏移。
第二種情況:如果這個page是一個特殊的進程將要釋放的一個page塊,則這是一個將要釋放的page塊的序列值,這個值在__free_page_ok()函數中設置。
*/
            pgoff_t index;      /* Our offset within mapping. */

            void *freelist;     /* slub/slob first free object */
            bool pfmemalloc;    /* If set by the page allocator,
                         * ALLOC_NO_WATERMARKS was set
                         * and the low watermark was not
                         * met implying that the system
                         * is under some pressure. The
                         * caller should try ensure
                         * this page is only used to
                         * free other pages.
                         */
        };

        union {
#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
            /* Used for cmpxchg_double in slub */
            unsigned long counters;
#else
            /*
             * Keep _count separate from slub cmpxchg_double data.
             * As the rest of the double word is protected by
             * slab_lock but _count is not.
             */
            unsigned counters;
#endif

            struct {

                union {
                    /*
                     * Count of ptes mapped in
                     * mms, to show when page is
                     * mapped & limit reverse map
                     * searches.
                     *
                     * Used also for tail pages
                     * refcounting instead of
                     * _count. Tail pages cannot
                     * be mapped and keeping the
                     * tail page _count zero at
                     * all times guarantees
                     * get_page_unless_zero() will
                     * never succeed on tail
                     * pages.
                     */
                    atomic_t _mapcount;   //_mapcount字段存放引用頁框的頁表項數目,確定其是否共享;

                    struct { /* SLUB */
                        unsigned inuse:16;
                        unsigned objects:15;
                        unsigned frozen:1;
                    };
                    int units;  /* SLOB */
                };
                atomic_t _count;        /* page的訪問計數,當爲0是,說明page是空閒的,當大於0的時候,說明page被一個或多個進程真正使用或者kernel用於在等待I/O*/
/*_count 字段和_mapcount
字段都是引用計數,它們用來共同維護 page 頁面的生命期。_mapcount 表示一個頁面
擁有多少頁表項指向它,_count 被稱爲 page 的使用計數,所有的_mapcount 計數只
相當於_count 計數中的一次計數。如果內核代碼中某執行序列在訪問某個頁面時需要
確保該頁面存在,則在訪問前給_count 計數加一,訪問結束後_count 計數減一。當
_count 計數減到負數時表示沒有任何內核需要使用該頁面,則表示該頁面沒被使用。
內核代碼不應該直接訪問_count 計數,而應該使用 page_count 函數。該函數用一個
struct page 的指針做爲參數,當該頁空閒時函數返回 0,否則返回一個正數表示參數
指向的頁面正被使用。*/

         };
        };
    };

    /* Third double word block */
    union {
        struct list_head lru;   /* Pageout list, eg. active_list
                     * protected by zone->lru_lock !
                     */
        struct {        /* slub per cpu partial pages */
            struct page *next;  /* Next partial slab */
#ifdef CONFIG_64BIT
            int pages;  /* Nr of partial slabs left */
            int pobjects;   /* Approximate # of objects */
#else
            short int pages;
            short int pobjects;
#endif
        };

        struct list_head list;  /* slobs list of pages */
        struct slab *slab_page; /* slab fields */
    };

    /* Remainder is not double word aligned */
    union {
        unsigned long private;      /* Mapping-private opaque data:
                         * usually used for buffer_heads
                         * if PagePrivate set; used for
                         * swp_entry_t if PageSwapCache;
                         * indicates order in the buddy
                         * system if PG_buddy is set.
                         */
#if USE_SPLIT_PTLOCKS
        spinlock_t ptl;
#endif
        struct kmem_cache *slab_cache;  /* SL[AU]B: Pointer to slab */
        struct page *first_page;    /* Compound tail pages */
    };

    /*
     * On machines where all RAM is mapped into kernel address space,
     * we can simply calculate the virtual address. On machines with
     * highmem some memory is mapped into kernel virtual memory
     * dynamically, so we need a place to store that address.
     * Note that this field could be 16 bits on x86 ... ;)
     *
     * Architectures with slow multiplication can define
     * WANT_PAGE_VIRTUAL in asm/page.h
     */
#if defined(WANT_PAGE_VIRTUAL)
    void *virtual;          /* Kernel virtual address (NULL if
                       not kmapped, ie. highmem) */
#endif /* WANT_PAGE_VIRTUAL */
#ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS
    unsigned long debug_flags;  /* Use atomic bitops on this */
#endif
    struct task_struct *tsk_dirty;  /* task that sets this page dirty */

#ifdef CONFIG_KMEMCHECK
    /*
     * kmemcheck wants to track the status of each byte in a page; this
     * is a pointer to such a status block. NULL if not tracked.
     */
    void *shadow;
#endif

#ifdef LAST_NID_NOT_IN_PAGE_FLAGS
    int _last_nid;
#endif
#ifdef CONFIG_PAGE_OWNER
    int order;
    gfp_t gfp_mask;
    struct stack_trace trace;
    unsigned long trace_entries[8];
#endif
}

//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

<span style="font-size:18px;"><span style="font-size:12px;"></span></span><pre name="code" class="objc">mapping字段

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